In Springfield, the parts of the RoW that were sold off are definitely a problem, but there hasn't been any heavy construction on them insofar; they are all open areas still, and as such aren't nearly as much of a problem from a construction standpoint to rebuilding the Armory Branch. The RoW south of there, but north of the trail just needs brush/tree clearing and regrading, and also reclaiming some parking lots; though there are some problematic grade crossings that'd have to be installed. There's nothing particularly challenging about rebuilding the rest of the Armory Branch out of its current condition from a construction perspective, asides from the aforementioned grade crossings.
The real problem is political will; it is something that MassDOT has to be involved in, and as discussed before, they just don't care much about RoW preservation, nor helping freight operations like CTDOT does. There's just no way something like this can happen without a strong political force from both the private industry and the state, as the locals would certainly protest, especially since you have to reclaim some since-developed land.
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